6 ms·

Parasites may explain regional differences in intelligence

38 points by Rob-Goodier 16y ago

diziet 16y ago
I'm really curious as to how exactly they accounted for other factors. They say they compared findings to other studies that looked at other possible explanations, but quite many of them are certainly correlated if not caused by one another.
- joubert 16y ago
  one can deduce how two kinds of organisms have influenced each other by studying how their respective gene pools (have) co-evolve(d)
  - zppx 16y ago
    Statically the problem that he posed is still there, what are the variables they ignored when calculating the statistical significance of their hypothesis? I actually read the paper, and well, it was one of the worst that I have read in my entire life. In the end of the paper they wrote: "We are not arguing that global variation in intelligence is only caused by parasite stress." So why is the point of having a research about causation when various independent causes can exist and do not test how much the hypothetical cause affects the causation relationship in general? Should I publish a paper on intelligence and ice cream consumption by population in the last 50 years to show how ridiculous the entire situation is? Sounds like that sort of paper that someone publishes only so that his name get cited more times.
losethos 16y ago
this is tabloid shit aimed at people who obsess on IQ which is most readers here. Face-it, this is crack cocain for you.
T_S_ 16y ago
My first thought: which parasites make you smarter?
- misterbwong 16y ago
  Had the same thought, though the article says that the lack of infectious disease (parasites) would cause intelligence gain. The population of countries where disease is less of a problem wouldn't see the same benefit...
- joubert 16y ago
  Me too. Although, then we'd probably call that relationship symbiotic and not parasitic.
- gojomo 16y ago
  A local political establishment which will subsidize your technical education so that you can develop improved weapons systems?
anonymousDan 16y ago
Why wouldn't it simply be the case that more intelligent societies have been more successful at eradicating disease?
archer 16y ago
Correlation <> causation. IMHO they should be very careful before establishing a link between those two.
- Dove 16y ago
  You should read the article. They considered that. The correlation is about 67%, and the chance that it might have come about at random is less than one in 10,000. But correlation is not causation, so Mr Eppig and his colleagues tried to eliminate other possible explanations. Previous work has offered income, education, low levels of agricultural labour (which is replaced by more mentally stimulating jobs), climate (the challenge of surviving cold weather might provoke the evolution of intelligence) and even distance from humanity’s African homeland (novel environments could encourage greater intelligence) as explanations for national differences in IQ. However, all of these, except perhaps the last, are also likely to be linked to disease and, by careful statistical analysis, Mr Eppig and his colleagues show that all of them either disappear or are reduced to a small effect when the consequences of disease are taken into account. There is, moreover, direct evidence that infections and parasites affect cognition. Intestinal worms have been shown to do so on many occasions. Malaria, too, is bad for the brain. A study of children in Kenya who survived the cerebral version of the disease suggests that an eighth of them suffer long-term cognitive damage. In the view of Mr Eppig and his colleagues, however, it is the various bugs that cause diarrhoea which are the biggest threat. Diarrhoea strikes children hard. It accounts for a sixth of infant deaths, and even in those it does not kill it prevents the absorption of food at a time when the brain is growing and developing rapidly.
tokenadult 16y ago
Another HN participant told me about a reply to this latest paper by these authors. http://blogs.discovermagazine.com/notrocketscience/2010/06/29/does-national-iq-depend-on-parasite-infections-er/ http://blogs.discovermagazine.com/notrocketscience/2010/06/2... When I see gee-whiz news reports about science, even in very reputable publications like The Economist, I think to turn to Peter Norvig's article "Warning Signs in Experimental Design and Interpretation" http://norvig.com/experiment-design.html http://norvig.com/experiment-design.html to evaluate the research.
- bd 16y ago
  There is an interesting comment in the Discover post, where Carl Zimmer (author of popular science book on parasites) points out several studies from all around the world (Jamaica, China, Indonesia, Philippines) where they found children got smarter after de-worming: http://blogs.discovermagazine.com/notrocketscience/2010/06/29/does-national-iq-depend-on-parasite-infections-er/#comment-10704 http://blogs.discovermagazine.com/notrocketscience/2010/06/2...
awongh 16y ago
another reason to support universal health care: a smarter public
- ams6110 16y ago
  You presume that universal health care will lead to a healthier public
  - Retric 16y ago
    It's been successful in every country that has tried it. Granted, the US has a bad habit of poorly implemented government programs so who knows, we may be the first exception. PS: Medical outcomes are far more dependent on the average level of care than the peek level of care. EX: There is a lot of evidence that the average doctor is significantly more effective than a "high preforming" doctor that is sleep deprived.
    - anamax 16y ago
      > It's been successful in every country that has tried it. Doesn't that depend on the starting point? For example, NHS started during the post WWII depression in the UK. The US isn't starting from there. I'm trying to track down the stats, but I've heard that the US lifespan is world-longest if you adjust for accidents and homicide, two things that aren't affected by healthcare. > Granted, the US has a bad habit of poorly implemented government programs so who knows, we may be the first exception. The US govt gets the same amount of tax revenue per person as the "rich" EU countries. If the benefits are less ....
      - kragen 16y ago
        > I've heard that the US lifespan is world-longest if you adjust for accidents and homicide, two things that aren't affected by healthcare. Other measures of health care quality, such as infant mortality, are worse in the US than in many other countries. So I doubt it.
donaldc 16y ago
When looking at correlating factors, they should also include diet. I remember reading that some Central Asian countries, as recently as a decade ago, were losing more than 5 IQ points on average just to iodine deficiency.
JeffL 16y ago
The first thing I thought of is that if lack of diseases is what has been causing the rise in intelligence, then there's likely to be a ceiling that average intelligence will hit as countries become healthier, rather than some mysterious force continually increasing average intelligence forever. That makes me a little sad.
ars 16y ago
It's politically illegal to say that on average whites are smarter than blacks so instead they have this little gem: "....distance from humanity’s African homeland (novel environments could encourage greater intelligence)...."
- Ardit20 16y ago
  There are plenty of Blacks outside Africa and I hear that in South Africa there are loads of whites.
  - ars 16y ago
    If you look at the data you'll notice it's very noisy. And I bet the noise is entirely (or mostly) made up of race. Note that one of the things they did not control for was race. It's racist to say this, I know, and more importantly it's not nice. But if you are going to make a study, you have to deal with reality. Control for race, and then check the correlation with parasites.
    - starkfist 16y ago
      How do you control for race? My grandmother is Mexican. My grandfather is German. What "race" is my mom? What about me?
      - ars 16y ago
        You do the best you can. Perfection is not required.
    - Ardit20 16y ago
      If you control for race you are implying that there are racial differences. That, may or may not be true, most likely it is not true. Social sciences are adverse to rigorously investigate the issue because I think we have learned from the last century some fundamental things, the main one being that labelling an entire race as inferior is extremely dangerous. Besides, I am sure all races are infected by diseases and so too I am sure that the difference the further you go from Africa is not because of ones race but because societies are richer the further you go and thus have better sanitation. Moreover, I think that the unites states contains more black individuals than Europe, thus, if race had any effect, you would expect Europe to be more intelligent. Not that we in Europe aren't mind you :P

38 points by Rob-Goodier 16y ago

I'm really curious as to how exactly they accounted for other factors. They say they compared findings to other studies that looked at other possible explanations, but quite many of them are certainly correlated if not caused by one another.

joubert 16y ago
one can deduce how two kinds of organisms have influenced each other by studying how their respective gene pools (have) co-evolve(d)
- zppx 16y ago
  Statically the problem that he posed is still there, what are the variables they ignored when calculating the statistical significance of their hypothesis? I actually read the paper, and well, it was one of the worst that I have read in my entire life. In the end of the paper they wrote: "We are not arguing that global variation in intelligence is only caused by parasite stress." So why is the point of having a research about causation when various independent causes can exist and do not test how much the hypothetical cause affects the causation relationship in general? Should I publish a paper on intelligence and ice cream consumption by population in the last 50 years to show how ridiculous the entire situation is? Sounds like that sort of paper that someone publishes only so that his name get cited more times.

losethos 16y ago

this is tabloid shit aimed at people who obsess on IQ which is most readers here. Face-it, this is crack cocain for you.

T_S_ 16y ago

My first thought: which parasites make you smarter?

misterbwong 16y ago
Had the same thought, though the article says that the lack of infectious disease (parasites) would cause intelligence gain. The population of countries where disease is less of a problem wouldn't see the same benefit...
joubert 16y ago
Me too. Although, then we'd probably call that relationship symbiotic and not parasitic.
gojomo 16y ago
A local political establishment which will subsidize your technical education so that you can develop improved weapons systems?

anonymousDan 16y ago

Why wouldn't it simply be the case that more intelligent societies have been more successful at eradicating disease?

archer 16y ago

Correlation <> causation. IMHO they should be very careful before establishing a link between those two.

Dove 16y ago
You should read the article. They considered that. The correlation is about 67%, and the chance that it might have come about at random is less than one in 10,000. But correlation is not causation, so Mr Eppig and his colleagues tried to eliminate other possible explanations. Previous work has offered income, education, low levels of agricultural labour (which is replaced by more mentally stimulating jobs), climate (the challenge of surviving cold weather might provoke the evolution of intelligence) and even distance from humanity’s African homeland (novel environments could encourage greater intelligence) as explanations for national differences in IQ. However, all of these, except perhaps the last, are also likely to be linked to disease and, by careful statistical analysis, Mr Eppig and his colleagues show that all of them either disappear or are reduced to a small effect when the consequences of disease are taken into account. There is, moreover, direct evidence that infections and parasites affect cognition. Intestinal worms have been shown to do so on many occasions. Malaria, too, is bad for the brain. A study of children in Kenya who survived the cerebral version of the disease suggests that an eighth of them suffer long-term cognitive damage. In the view of Mr Eppig and his colleagues, however, it is the various bugs that cause diarrhoea which are the biggest threat. Diarrhoea strikes children hard. It accounts for a sixth of infant deaths, and even in those it does not kill it prevents the absorption of food at a time when the brain is growing and developing rapidly.

tokenadult 16y ago

Another HN participant told me about a reply to this latest paper by these authors. http://blogs.discovermagazine.com/notrocketscience/2010/06/29/does-national-iq-depend-on-parasite-infections-er/ http://blogs.discovermagazine.com/notrocketscience/2010/06/2... When I see gee-whiz news reports about science, even in very reputable publications like The Economist, I think to turn to Peter Norvig's article "Warning Signs in Experimental Design and Interpretation" http://norvig.com/experiment-design.html http://norvig.com/experiment-design.html to evaluate the research.

bd 16y ago
There is an interesting comment in the Discover post, where Carl Zimmer (author of popular science book on parasites) points out several studies from all around the world (Jamaica, China, Indonesia, Philippines) where they found children got smarter after de-worming: http://blogs.discovermagazine.com/notrocketscience/2010/06/29/does-national-iq-depend-on-parasite-infections-er/#comment-10704 http://blogs.discovermagazine.com/notrocketscience/2010/06/2...

awongh 16y ago

another reason to support universal health care: a smarter public

ams6110 16y ago
You presume that universal health care will lead to a healthier public
- Retric 16y ago
  It's been successful in every country that has tried it. Granted, the US has a bad habit of poorly implemented government programs so who knows, we may be the first exception. PS: Medical outcomes are far more dependent on the average level of care than the peek level of care. EX: There is a lot of evidence that the average doctor is significantly more effective than a "high preforming" doctor that is sleep deprived.
  - anamax 16y ago
    > It's been successful in every country that has tried it. Doesn't that depend on the starting point? For example, NHS started during the post WWII depression in the UK. The US isn't starting from there. I'm trying to track down the stats, but I've heard that the US lifespan is world-longest if you adjust for accidents and homicide, two things that aren't affected by healthcare. > Granted, the US has a bad habit of poorly implemented government programs so who knows, we may be the first exception. The US govt gets the same amount of tax revenue per person as the "rich" EU countries. If the benefits are less ....
    - kragen 16y ago
      > I've heard that the US lifespan is world-longest if you adjust for accidents and homicide, two things that aren't affected by healthcare. Other measures of health care quality, such as infant mortality, are worse in the US than in many other countries. So I doubt it.

donaldc 16y ago

When looking at correlating factors, they should also include diet. I remember reading that some Central Asian countries, as recently as a decade ago, were losing more than 5 IQ points on average just to iodine deficiency.

JeffL 16y ago

The first thing I thought of is that if lack of diseases is what has been causing the rise in intelligence, then there's likely to be a ceiling that average intelligence will hit as countries become healthier, rather than some mysterious force continually increasing average intelligence forever. That makes me a little sad.

ars 16y ago

It's politically illegal to say that on average whites are smarter than blacks so instead they have this little gem: "....distance from humanity’s African homeland (novel environments could encourage greater intelligence)...."

Ardit20 16y ago
There are plenty of Blacks outside Africa and I hear that in South Africa there are loads of whites.
- ars 16y ago
  If you look at the data you'll notice it's very noisy. And I bet the noise is entirely (or mostly) made up of race. Note that one of the things they did not control for was race. It's racist to say this, I know, and more importantly it's not nice. But if you are going to make a study, you have to deal with reality. Control for race, and then check the correlation with parasites.
  - starkfist 16y ago
    How do you control for race? My grandmother is Mexican. My grandfather is German. What "race" is my mom? What about me?
    - ars 16y ago
      You do the best you can. Perfection is not required.
  - Ardit20 16y ago
    If you control for race you are implying that there are racial differences. That, may or may not be true, most likely it is not true. Social sciences are adverse to rigorously investigate the issue because I think we have learned from the last century some fundamental things, the main one being that labelling an entire race as inferior is extremely dangerous. Besides, I am sure all races are infected by diseases and so too I am sure that the difference the further you go from Africa is not because of ones race but because societies are richer the further you go and thus have better sanitation. Moreover, I think that the unites states contains more black individuals than Europe, thus, if race had any effect, you would expect Europe to be more intelligent. Not that we in Europe aren't mind you :P